Difficulties in the determination of post-liquefaction strength for sand

Static liquefaction has been considered one of the commonest failure mechanisms for granular soil slopes or tailings dams. One of the design approaches adopted is based on the so-called post-liquefaction strength as a design parameter. However, determination of the post-liquefaction strength by laboratory tests is problematic. In this paper, experimental data are used to illustrate that the post-liquefaction strength cannot be determined properly or uniquely in the laboratory. The assumption of an undrained condition is also questionable for sand or tailings with relatively high permeability under static loading conditions. Due to the above deficiencies, it is recommended that engineers stop using the post-liquefaction strength as a design parameter in practice.